Certina Watches Under 40mm

424 Certina models in the 0–40mm range, actually measuring 2mm to 39mm. Compact sizing that suits smaller wrists and dressier looks.

Thickness is where they separate: 6.9mm to 15.9mm. That 9mm gap decides whether a watch slides under a shirt sleeve.

361 are round and 31 rectangular — at the same nominal width, a rectangular case covers noticeably more wrist.

Releases run from 2002 to 2025, so this mixes current models with older references.